This invention relates to a solenoid actuated valve, and will have application to a solenoid valve which is easily flushed and conserves fluids passing therethrough.
Linear proportional solenoid valves are shown and described in several U.S. patents, many of which are owned by the assignee of this invention. Particular attention is drawn to U.S. Pat. No. 4,711,269 which is exemplary of this art field. In each of these patents, similarly to the solenoid employed with this invention, the solenoid coil surrounds the pole piece. Likewise, each of the aforementioned patents incorporates a central helical spring which urges the valve into a closed position.
Solenoid actuated diaphragm valves are commonly used to control and regulate the flow of fluids. The fluid can be isolated and channeled to selected chambers within the valve by means of the diaphragm. Such devices are referred to within the industry as isolation valves.
The flow path within the valve is regulated by the use of a solenoid to move the pole piece and the associated diaphragm. The diaphragm also serves as a seal to prevent fluid from entering the internal passages within the solenoid.
All diaphragm isolation valves have some internal volume within the flow path of the valve. The volume of fluid that is purged during a valving cycle is referred to as the working volume. The problem arises in that this volume of fluid may not be completely purged during a valve cycle. The volume of fluid that is not purged during the valve cycle is referred to as dead volume. Dead volume is undesirable, and it is this volume that designers of valves strive to minimize.
Typically, the sealing qualities of the diaphragm valve are a function of the diaphragm material and the poppet and seat geometry. The geometry of the poppet and the valve seat also determine the susceptibility to particulate contamination.
Present contaminant resistant bypass valves use a high force shear load approach to the elimination of problems related to particulates which inhibits the function of the valve seal and may entrap fluid or particulate matter within the valve.
Particulate contamination of a valve seat area can cause valve leakage. Accordingly, it is desirable to flush the valve seat and the diaphragm with each valve cycle, in order to remove particles from the passage and from the valve seat.
This is particularly important in the medical field, where, for example, medication is introduced into a continuing flow of fluid to the body of a patient.